Refreshable Braille Display Device

ABSTRACT

Disclosed is a refreshable Braille display device comprised of a rotary character display assembly which can display a refreshable Braille character in the plane of the rotary display assembly. Also disclosed is a method of displaying a refreshable Braille character.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of and claims the benefit of priorityto co-pending U.S. patent application Ser. No. 12/820,922, filed Jun.22, 2010, which application is a continuation of U.S. patent applicationSer. No. 11/567,700, filed Dec. 6, 2006, which application claims thebenefit of priority to U.S. Provisional Patent Application Ser. No.60/748,003; filed Dec. 6, 2005. The entire disclosures of these patentapplications are incorporated by reference herein for all purposes.

FIELD OF THE INVENTION

The present invention relates generally to the field of refreshableBraille display devices and more particularly to a refreshable Brailledisplay device comprised of a rotary display assembly.

BACKGROUND OF THE INVENTION

Braille is the language of visually impaired readers whose vision isimpaired to the extent that they cannot read printed material. ReadingBraille relies on the sense of touch, where reading is done by running afinger over a combination of characters. This method was invented byLouise Braille (1809-1852) in 1821 at the age of 12. Louise Braillebecame visually impaired at the age of 3 and developed this method toenable him to live equally with the people around him.

A typical Braille character is comprised of six raised pins or bumps ina Braille cell grid having three rows high and two columns wide.Different combinations of the six pins represent different characters.In other applications, a Braille cell may be comprised of 8 or moreBraille dots arranged in a grid four or more rows high and two columnswide. For example, the word “hello” in a typical six pin Braille cell isshown below.

Refreshable Braille Displays (RBDs) are devices that allow visuallyimpaired readers to review work or read material, which an enabledreader can do on a computer screen. Refreshable Braille Displays rangein terms of the number of characters presented on one line, but moststandard displays can present in the range of from 40 to 80 cellcharacters.

Unfortunately, many visually-impaired citizens around the country areforced to use the traditional audio device method to review work or readmaterial due to the scarce supply and high cost of RBD's. This problemstems from the fact that the Braille displays currently on the marketare very expensive to produce and maintain. These devices typicallyutilize a dedicated Piezoelectric crystal actuator for each raisedcharacter dot in a cell grid. These Piezoelectric actuators expand whenan electric potential is applied to them, producing a change in themechanism leading to a protruding bump. Repairs are also expensive andinconvenient because they require the user to relinquish their unit forthe duration of the repair and because of the complexity and intricacyof the Piezoelectric actuators of the RBD unit itself.

Improvement in such devices producing computer-refreshable Braille textfor tactile reading by the blind and visually impaired could thus beutilized thereby broadening accessibility to computer services such aselectronic books, e-mail and other network access, and general computeruse. Improvements in cost and mechanical reliability must be attained inorder to facilitate more widespread use of refreshable Braille devices.Thus, there is a need in the art for a refreshable Braille displaydevice which can reduce the overall cost to the consumer and stillaccurately display and refresh a set of Braille characters, occupy lessspace than existing RBDs, be easy to clean, be tactilely andaesthetically pleasing, and produce no objectionable noise.

SUMMARY OF THE INVENTION

The present invention is based, in part, upon the invention of animproved refreshable Braille display device comprised of a rotarycharacter display assembly which can display any desired number ofrefreshable Braille characters in the plane of the rotary displayassembly.

In one aspect, the refreshable Braille display device comprises aBraille character display assembly having a lower rotary plate defininga plurality of lower bearing wells, each lower bearing well configuredto house a bearing; an upper rotary plate having a substantially planarreading surface and defining a plurality of upper bearing wellsconfigured to receive a bearing, the upper rotary plate being positionedin overlying registration with and connected to the lower rotary platesuch that each upper bearing well is in overlying registration with oneof the plurality of lower bearing wells to provide a plurality ofbearing chambers, wherein the plurality of bearing chambers each have abearing disposed therein and form at least one Braille character cellarray configured to rotate about, and in a plane substantiallyperpendicular to, a rotary axis. A stationary divider plate is disposedbetween the lower and upper rotary plates and defines a plurality ofapertures configured to selectively allow communication between therespective bearing wells when a lower bearing well and an upper bearingwell are each positioned in registration with one of the plurality ofapertures. A means is also provided for selectively positioning thebearing in at least one bearing chamber in the respective upper or lowerbearing wells of the character cell array when communication between therespective bearing wells is selectively allowed.

In another aspect, the present invention provides a method of displayinga refreshable Braille character. The method generally comprisesproviding a substantially planar Braille character display assemblycomprising a plurality of bearing chambers, wherein the plurality ofbearing chambers each have a bearing disposed therein and form aplurality of Braille character cell arrays configured to rotate about,and in a plane substantially perpendicular to, a rotary axis;positioning at least one of the plurality of bearing chambers of theBraille character cell array in registration with a means forselectively positioning a bearing; selectively positioning the bearingin the bearing chamber in an upper portion of the bearing chamber todisplay a raised Braille character dot; and maintaining the selectivelypositioned bearing of step c) in the upper portion of the bearingchamber while the substantially planar Braille character displayassembly is rotated at least one revolution about the rotary axis.

Additional aspects of the invention will be set forth, in part, in thedetailed description, and any claims which follow, and in part will bederived from the detailed description, or can be learned by practice ofthe invention. It is to be understood that both the foregoing generaldescription and the following detailed description are exemplary andexplanatory only and are not restrictive of the invention as disclosedand/or as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute apart of this specification, illustrate certain aspects of the instantinvention and together with the description, serve to explain, withoutlimitation, the principles of the invention. Unless indicated otherwise,like numerals represent like elements.

FIG. 1 is a perspective view of an exemplary refreshable Braille displaydevice according to one aspect of the present invention.

FIG. 2 is an exploded perspective view of an exemplary Braille characterdisplay assembly according to one aspect of the present invention.

FIG. 3 is a schematic cutaway side view of an exemplary Braillecharacter display assembly according to one aspect of the presentinvention.

FIG. 4 is schematic top view of an exemplary stationary divider plateaccording to one aspect of the present invention.

FIG. 5 a perspective view of an exemplary refreshable Braille displaydevice according to one aspect of the present invention.

FIG. 6 is top view of an exemplary timing plate according to one aspectof the present invention.

FIG. 6 a is a close up illustration of the exemplary timing apertures asshown in FIG. 6

FIG. 6 b is an in illustration of exemplary timing apertures having atapered configuration in a circumferential direction.

FIG. 7 is an illustration of an exemplary refreshable Braille devicecomprising a means for timing or regulating the selective positioning ofa character bearing according to one aspect of the present invention.

FIG. 8 is schematic cutaway side view of an exemplary light detectionassembly according to one aspect of the present invention.

FIG. 9 is a schematic wiring diagram according to one aspect of thepresent invention.

FIG. 10 is an exploded perspective view of an exemplary refreshableBraille display device comprising a base assembly according to oneaspect of the present invention.

FIGS. 11 a-11 g schematically illustrate a sequence of the activation ofall six Braille dots in a single Braille cell according to one aspect ofthe present invention.

FIG. 12 is an exemplary illustration of the variable in Equation (I).

FIG. 13 is an illustration of the two unknowns r and θ being solvedaccording to Equation (II).

FIG. 14 is a free-body diagram of an accelerating ball bearing accordingto Equation (VII).

DETAILED DESCRIPTION OF THE INVENTION

The present invention can be understood more readily by reference to thefollowing detailed description, examples, and claims, and their previousand following description. However, before the present compositions,devices, and/or methods are disclosed and described, it is to beunderstood that this invention is not limited to the specific articles,devices, and/or methods disclosed unless otherwise specified, as suchcan, of course, vary. It is also to be understood that the terminologyused herein is for the purpose of describing particular aspects only andis not intended to be limiting.

The following description of the invention is provided as an enablingteaching of the invention in its best, currently known embodiment. Tothis end, those skilled in the relevant art will recognize andappreciate that many changes can be made to the various aspects of theinvention described herein, while still obtaining the beneficial resultsof the present invention. It will also be apparent that some of thedesired benefits of the present invention can be obtained by selectingsome of the features of the present invention without utilizing otherfeatures. Accordingly, those who work in the art will recognize thatmany modifications and adaptations to the present invention are possibleand can even be desirable in certain circumstances and are a part of thepresent invention. Thus, the following description is provided asillustrative of the principles of the present invention and not inlimitation thereof.

As used herein, the singular forms “a,” “an” and “the” include pluralreferents unless the context clearly dictates otherwise. Thus, forexample, reference to a “ball bearing” includes aspects having two ormore such ball bearings unless the context clearly indicates otherwise.

Ranges can be expressed herein as from “about” one particular value,and/or to “about” another particular value. When such a range isexpressed, another aspect includes from the one particular value and/orto the other particular value. Similarly, when values are expressed asapproximations, by use of the antecedent “about,” it will be understoodthat the particular value forms another aspect. It will be furtherunderstood that the endpoints of each of the ranges are significant bothin relation to the other endpoint, and independently of the otherendpoint.

As used herein, the terms “optional” or “optionally” mean that thesubsequently described event or circumstance may or may not occur, andthat the description includes instances where said event or circumstanceoccurs and instances where it does not.

As summarized above, the present invention provides a refreshableBraille display device comprised of a rotary character display assemblywhich can display a refreshable Braille character in the plane of therotary display assembly. With reference to FIG. 1, an exemplaryrefreshable Braille display device 100 is shown. The exemplified displaydevice generally comprises a rotary display assembly 200 configured torotate about, and in a plane substantially perpendicular to, a rotaryaxis R. The rotary display assembly is configured to display a pluralityof refreshable Braille character cells 210 that can rotate about therotary axis and in the plane of the rotary display assembly.

As shown in FIG. 2, the rotary display assembly 200 is comprised of alower rotary plate 220 having a plurality of lower bearing wells 222formed therein. Each lower bearing well is configured to house one of aplurality of bearings 230. An upper rotary plate 240, having a pluralityof upper bearing wells 242 configured to received one of the pluralityof bearings, is positioned in overlying registration with the lowerrotary plate. As shown in FIG. 3, the upper bearing wells and lowerbearing wells, when positioned in overlying registration, form aplurality of bearing chambers 250. The plurality of bearing chambers arespatially arranged to form the plurality of Braille character cells 210.In particular, each Braille character cell is comprised of an array ofbearing chambers positioned circumferentially about the rotational axis.For example, as shown, each Braille character cell can comprise an arrayof six bearing chambers positioned in a conventional Braille cell gridhaving three rows high and two columns wide. In use, one or morebearings 230, housed within one or more respective bearing chambers, canbe selectively positioned in a raised or lowered position to display adesired combination of character dots and thus a desired Braillecharacter.

As shown for example in FIG. 3, a stationary divider plate 260 isdisposed between the lower and upper rotary plates and separates thebearing chambers into an upper portion 252 and a lower portion 254. Thestationary divider plate also defines a plurality of pass throughapertures 262 configured to selectively allow communication between therespective upper and lower bearing wells when a lower bearing well andan upper bearing well are each rotated into registration with one of theplurality of pass through apertures 262. In use, the stationary plateenables the plurality of bearings housed within the bearing chambers tobe selectively positioned in either the upper chamber portion (raisedposition) or the lower chamber portion (down position) depending onwhich Braille character is to be displayed. Once positioned, a bearingwill then remain in the respective upper or lower portion of a bearingchamber until the bearing is selectively repositioned in the opposingportion of a bearing chamber.

An exemplary stationary plate is also depicted in FIG. 4. As shown, thestationary divider plate can comprise a plurality of pass-throughapertures 262 defined therein that are sized and shaped to allow theselective passage of bearing there through. Thus, by allowing theselective passage of a ball bearing through an aperture in thestationary divider plate, a ball bearing can selectively pass from thelower bearing chamber portion to the opposed upper chamber portion andvice versa through a pass through aperture defined by the stationarydivider plate. In one aspect, the number of pass through apertures isdependent upon and can correspond to the number of rows of Braille dotsin the Braille character cell. For example, in an aspect comprising sixBraille dot character cell having array of 3 dots high and two dotswide, the stationary divider plate can define three pass throughapertures. Alternatively, in an aspect comprising an 8 Braille dotcharacter cell having 4 dots high and two wide, the stationary dividerplate can define four pass through apertures. As further shown in FIG.4, the exemplified three pass through apertures 262 can each bepositioned at differing distances D1, D2 and D3 from the rotationalaxis. According to this aspect, each distance D1, D2, and D3 can beselected so that each row of bearing chambers of the Braille charactercell will, when rotated, pass in communication with a pass throughaperture dedicated to that row of bearing chambers.

The stationary divider plate can further be configured such that passthough aperture(s) can be aligned with a means for selectivelypositioning a bearing in the upper portion of the bearing chamber. Forexample, as will be described in more detail below, in one embodiment anelectromagnet assembly can be used to selectively position a bearing inthe upper portion of a bearing chamber when the respective upper andlower bearing wells are aligned in registration with a pass-throughaperture. Therefore, according to this aspect, the pass throughaperture(s) of the stationary divider plate should also be aligned withthe electromagnet.

In one aspect, it is preferable for the stationary divider plate to havethe thinnest allowable thickness in order to minimize the distance oftravel between the lower position of the ball bearings and the upperposition. The plate should however, be substantially rigid so that itdoes not deflect or deform when the user is reading and pushing down onthe character dots. Optionally, the plate can be non-ferric so that itdoes not interfere with the magnetism involved in actuating or pulling aball bearing upwards into the raised or actuated position. To this end,in an exemplary aspect, and not meant to be limiting, the stationarydivider plate can be comprised of a copper plate, which is non-ferric,relatively stiff and rigid, and can have a relatively thin thickness ascompared to the majority of the plastic or polymeric materialsexhibiting the same characteristics. In addition, a copper plate canprovide a relatively smooth surface which can reduce the friction of theball bearings that roll on it. In an exemplary aspect, the thickness ofthe copper plate can be approximately 0.02 inches.

It is contemplated that the apertures can be configured in any desiredshape, such as for example, a substantially circular hole, or anelongated slot. In the exemplified aspect, the pass through aperturescan be substantially circular having a diameter selected to be largeenough to allow a ball bearing to selectively pass through the aperturebut small enough not to allow adjacent ball bearings to pass through atthe same time. In an exemplary aspect, the pass through aperture can beapproximately 3.26 mm in diameter.

The dimensions of the upper and lower rotary plates, including thediameter of the plates, thickness of the plates, and the dimensions andspacing of the Braille character cells, will be dependent in part, uponthe number of character cells desired, and the size of the Braillecharacters desired. In an exemplified aspect, these dimensions can bederived directly from the standard Jumbo American Braille dimensions.Thus, in one aspect, and without limitation, the cell-to-cell spacingfor an exemplified device comprising 30 character cells can beapproximately 8.76 mm.

Based upon the exemplified cell to cell character spacing set forthabove, the following calculations can then be used to determine thedesired diameter for the upper rotary plate. Specifically, the referenceradius can be taken to be the middle row of the Braille character cell.As the exemplary distance between the exemplified cells are 8.76 mmapart, when the cells are arranged in a circular pattern, the Brailledots in the upper corners of adjacent Braille character cells becomecloser together and the lower ones become further apart from each other.By taking the middle row of the Braille characters as the referencepoint, the difference in Braille character spacing is apportioned.Accordingly, using equations of the arcs, Equations (I) can be used tocalculate the reference radius.

$\begin{matrix}{r = \frac{8.76(360)}{2\pi \; \theta}} & \left\lbrack {{Equation}\mspace{14mu} (I)} \right\rbrack\end{matrix}$

Where r is the reference radius,

$\theta = \frac{360}{n}$

where n is the number of cells on the disk. An exemplary illustration ofthe variables in the Equation (I) is set forth in FIG. 12. Using theequation (I) above, an exemplary display device comprising 30 Braillecharacter cells and having a cell separation of approximately 8.76 mmprovides a reference radius of 41.83 mm. If desired, an added distancecushion can also be added to the reference radius to provide a cushionfor a user to manually rotate the display assembly. In one aspect, thecushion can be approximately 20 mm added to the calculated referenceradius. It will also be appreciated that the angular separation betweenthe character cells in a circumferentially spaced arrangement willdepend on the number of character cells. To that end, the exemplaryaspect comprised of 30 character cells will have a separation angle ofapproximately 12°. Using the exemplary procedure set forth above, one ofordinary skill in the art will be able to arrive at the desired size ofthe top rotary disk without requiring any undue experimentation.

In one aspect, the lower rotary plates can be sized and shaped to be atleast substantially the same dimension as the top rotary plate.Additionally, in a further aspect, the lower rotary plate can alsocomprise a larger or smaller radius than the top rotary track plate inorder to, for example, accommodate for additional features of thedisplay device, such as the timing plate apertures that discussed indetail below.

The dimensions and the spacing of the upper and lower bearing wellsforming the bearing chambers where the ball bearings are housed can alsobe determined according to the Jumbo American Braille dimensions, aswell as taking into account any optional manufacturing tolerances. Forexample, the dot base diameter of a Jumbo American Braille dot isapproximately 1.7 mm and the protrusion height of the dot from thesurface is approximately 0.5 mm. As this is the diameter of the actualdot, the well diameter would therefore need to be slightly larger. Thus,a bearing well diameter of approximately 2.16 mm can provide a raiseddot resulting in a similar profile to that of the Jumbo American Brailledot.

The upper and lower rotary plates can manufactured from any desiredmaterials, including for example, plastic or acrylic. The upper andlower rotary plates can also be configured to have any desired thicknesswhich can, in part depend on the size of a particular bearing to behoused within a formed bearing well. For example, in one aspect it isdesired for the lower plate to have a thickness sufficient to formbearing wells capable of housing at least substantially the entirebearing received therein. Thus, according to this aspect, the lowerrotary plate can have a thickness at least equal to or greater than thediameter of a desired bearing. Further, it should also be understoodthat the lower plate can further be comprised of a plurality of plateshaving thickness which, in combination provide a desired thickness.Likewise, in one aspect, the thickness of the upper rotary plate is lessthan that of a desired bearing diameter so that a bearing in the raisedposition and resting on the stationary divider plate will protrudebeyond the surface of the top rotary plate resulting in a raised bump orpimple forming a dot of the Braille character cell. To this end, in anexemplary aspect, and without limitation, the upper rotary plate can beapproximately 1/16″ thick and the lower rotary plate can beapproximately 3/32″ thick.

The refreshable display device of the present invention can also beconfigured to provide any desired number of refreshable Braillecharacter cells. For example, the device can be configured to comprisefrom 1 to several hundred Braille character cells, including for example10, 20, 30, 40, 50, 60, 70, 80, 90, 100, or even 200 or more charactercells. In still another aspect, and as exemplified herein, a refreshableBraille display device of the present invention can comprise 30 Braillecharacter cells.

Likewise, the number of raised character dots and hence the number ofball bearings can be dependent upon the number of character cells in therotary display assembly. For example, as stated above a conventionalprinted Braille character cells comprise a grid of six dots. Thus,according to this aspect, the number of ball bearings can beproportional to the number of character cells by a factor of 6.Accordingly, in the exemplified aspect comprised of 30 character cells,the rotary display device further comprises 180 ball bearings.

The ball bearings can be of any desired size suitable for providing araised character dot in a legible Braille character cell. In one aspect,and as exemplified herein, the ball bearings are sized and shaped toprovide a Braille dot that conforms to the recognized standards of theJumbo American Braille dimension, having for example an approximateraised dot height of 0.5 mm and an approximately raised dot base radiusof 0.85 mm. Accordingly, a particular ball bearing providing theexemplified raised character dot parameters exemplified above can becalculated according to the procedure set forth below. It should beunderstood that in view of the exemplary calculation procedure, one ofordinary skill in the art will be able to determine an appropriate ballbearing based upon the particular raised character dot parametersdesired. In particular, using the Equation (II) below and solving forthe two unknowns r and θ as illustrated in FIG. 13, the diameter of aball bearing that will provide the desired raised dot parameters can becalculated. The 0.5 mm is the exemplary height of the ball bearingprotruding from the upper plate and the 0.85 mm is the exemplary radiusof the Jumbo American Braille dimension for the diameter.

r sin θ=r−0.5 mm

r cos θ=0.85 mm   [Equation II]

From these calculations, an exemplary ball bearing can have a diameterof approximately 1.945 mm. To this end, a conventional commerciallyavailable 2 mm diameter ball bearing will have an insignificantdeviation from the calculated diameter and can be used as an exemplarybearing suitable for use in the present invention.

The ball bearings can be comprised of any desired material. However, inone aspect the bearings are comprised of a metallic material, such asany conventional ferrous metal, in order to be magnetically attracted byan electromagnetic actuator discussed in more detail below. Further, theball bearing surface should, in one aspect, be smooth in order to easilyroll over the top surface of the stationary divider mentioned above anddiscussed in more detail below. Accordingly, in one aspect, the ballbearings can be comprised of chrome-plated carbon steel such as the 2 mmchrome-plated steel ball bearings available from Small Parts, Inc. ofMiami Lakes, Fla., USA (Part No. BS-M02-C). In still another aspect, theball bearing can be comprised of a nickel-alloy combination.

In still a further aspect, a protective film or sheet 270 can also beapplied to the top surface of the upper rotary plate in order to preventthe ball bearings from coming out of the display. The protective sheetcan be formed of any desired material that is flexible enough to conformto the spherical contour of a raised ball bearing and tough enough sothat it won't break with excessive use. To this end, in one aspect theprotective film can be a latex layer. The latex layer can have anydesired thickness, including for example, approximately 0.006″, 0.010″,or even 0.025″. As will be appreciated upon practicing the presentinvention, the latex layer can also provide the added benefit of a softfeel for enhanced legibility. In addition, the latex layer can alsoprevent dirt and other contaminants from passing through the ballbearing pass through apertures.

The protective film such as a latex sheet can be attached to the displayor reading surface of the upper rotary plate using any common craftspray adhesive such as Elmer's spray adhesive and, if needed, can thenbe trimmed to the appropriate dimensions. An exemplary latex sheet canbe formed from 0.010″ thick latex sheet from Small Parts, Inc. (Part No.SLR-010-B).

The refreshable display device further comprises a means for selectivelypositioning the bearings of a character cell array in a raised orlowered position when communication between the respective bearing wellsis selectively allowed. For example, in one aspect and as shown in FIG.5, the means for selectively positioning a bearing can comprise anelectromagnetic actuator assembly 500 configured to magnetically attracta metallic bearing. According to this aspect, a bearing housed in alower bearing chamber portion (lower bearing well) can be magneticallyattracted by an electromagnet and thus selectively raised into an upperchamber portion by the electromagnet. Alternatively, a bearing housed inan upper portion of a bearing chamber can be retained in a raisedposition by the electromagnet. Still further, a raised bearing can berefreshed or repositioned back to a lower bearing well by allowing thebearing to drop back to a lower portion under the force of gravity. Inuse, each bearing can be selectively positioned in a raised positionsuch that the raised bearing forms a raised dot on the surface of therotary display assembly. By selectively actuating or positioning anydesired combination of the bearings within a Braille character cell intoa raised position, any character of the Braille language can be providedon the surface of the rotary display.

The electromagnetic actuator assembly can comprise any conventionalelectromagnet or device that produces the same effect that is capable oflifting a ball bearing by applying a magnetic field that attracts theball bearing upwards. In order to provide the largest lifting power tothe ball bearings, the tip of the electromagnet can, for example, bepositioned as close as 1 mm over the top of the upper rotary plate. Theexemplary 1 mm spacing further accommodates for the exemplary 0.5 mmprotrusion of the ball bearings, leaving an exemplary 0.5 mm safetyfactor so that there would be no collision between both surfaces. In oneaspect, the actuators are not put inline to actuate the three rowcolumns of the characters but rather are staggered around thecircumference of the reader. Thus, in one aspect, the electromagnet ofthe middle row of Braille dots can be positioned opposite the readingsite and the left and right electromagnet that actuates the upper andlower rows of Braille dots can be positioned approximately 60° apartfrom each side of the middle electromagnet. This configuration can allowthe desired Braille cell to be completely displayed before reaching thereading site.

The electromagnetic actuators should be selected to also provide asufficient magnetic activation force capable of drawing the ball bearinginto the actuated position quickly enough before the next character cellis to be actuated. To this end, the requisite level of actuation forcewill depend upon several factors including the bearing size and weight,the distance a bearing will travel, the desired rotation speed of adisplay device, and others that will be known to one of ordinary skillin the art. Accordingly, using the exemplified display device of thepresent invention as an example, the requisite actuation force can becalculated as set forth below.

First, the length that the ball needs to travel, x, is given by Equation(III):

x=½d _(l) +d _(t) +t _(Cu)   [Equation (III)]

In the exemplified aspect, d_(l) is the depth of the lower bearing welland is equal to ⅛″, d_(t) is the thickness of the top bearing well andis equal to 1/16″, and t_(Cu) is the thickness of the copper middletrack and is equal to about 0.02″. Accordingly, in the exemplifieddisplay device described herein, the traveling length of the ballbearing from the non-actuated position to the actuated position isapproximately 0.146″, or 3.7084 mm.

The time allowed for actuation before the actuation of the next dot canalso be calculated as set forth below. In particular, a very fast orskilled Braille reader can read approximately 120 words per minute.Thus, with an average word length of five characters, a skilled readercan read up to 600 characters per minute. Accordingly, to support a fastBraille reading rate of approximately 600 characters per minute, anexemplified display comprising 30 characters or Braille cells would havea rotational speed of approximately 20 rpm (rotations per minute).

For an exemplary display having a radius to the outer row of Braillecharacter dots of approximately 44.75 mm, the maximum possibly velocityof the balls bearings, which occurs at the outer radius, is given byEquation (IV):

v_(max)=ω_(max)r_(outer)   [Equation (IV)]

This gives a maximum velocity of approximately 0.0938 m/s. From thedistance traveled and the velocity, the time allowed for actuation canthen be calculated as the quotient of the two. Therefore, the allowabletime for actuation in one aspect as described herein can be 0.0266875seconds.

Given the distance and time traveled, Equation (V) of one-dimensionalkinematics can be applied to determine the acceleration, a, necessary:

$\begin{matrix}{x = {{\frac{a}{2}t^{2}} + {v_{0}t} + x_{0}}} & \left\lbrack {{Equation}\mspace{14mu} (V)} \right\rbrack\end{matrix}$

Where v₀ is the initial velocity and is equal to zero and x₀ is theoriginal height and is also equal to zero. Simplifying the equation andsolving for a gives a minimum necessary acceleration of approximately10.4136 m/s². This is equal to the acceleration term in Newton's SecondLaw of Motion shown in Equation (VI):

ΣF=ma   [Equation (VI)]

The corresponding free-body diagram of the accelerating ball bearing isshown in FIG. 14, where F_(M) is the force exerted by the electromagnetand mg is the force of gravity. Substituting these values into Equation(VI), the equation simplifies to Equation (VII):

F _(M) −mg=ma   [Equation (VII)]

Therefore, in order to obtain the minimum electromagnetic force requiredfor a successful actuation, the mass of the ball bearing should becalculated. The ball bearings as exemplified for purposes of this samplecalculation have a diameter of 3/32″, which yields a volume of4.3143×10⁻⁴ in³. The density of the ball bearings used is 0.283 lbs/in³(the approximate density of steel), which yields a mass of 1.221×10⁻⁴lbs, or 5.5498×10⁻⁵ kg. Substituting this mass value into Equation (VII)and solving for F_(M) yields a minimum electromagnetic force required ofF_(M)=0.0011 N. Using this sample calculation, one of ordinary skill inthe art will be able to determine an electromagnet that will supply therequisite activation force for a refreshable Braille display devicecomprising a desired dimension and materials without requiring any undueexperimentation. Following actuation, the character dots can then berefreshed or dropped to the lowered state by the force of gravity. Tothis end, the acceleration due to free-fall is roughly 9.81 m/s², whichis within the acceptable tolerance of the exemplary minimum accelerationrequired of 10.4136 m/s² as calculated above. However, in still anotheraspect, refreshing the ball bearings from the top position to the bottomposition could be accomplished using a permanent magnet or an activatedelectromagnetic positioned below the pass-through aperture in thestationary divider plate that would provide a gravity-assist force tomove the ball bearing from the top position to the bottom position.

In still another aspect, the refreshable Braille display device of thepresent invention can further comprise a means for timing or regulatingthe selective actuation or positioning of a ball bearing. The timingmeans can be any mechanism or system capable of selectively triggeringthe selective actuation or positioning of a ball bearing. For example,the rotary display assembly can further comprise a rotary timing plate.The timing plate can be provided to regulate and ensure a selected setof ball bearings are selectively positioned at the correct sequence intime. As shown in FIG. 6, an exemplary timing disk 600 can define aplurality of timing apertures 610 positioned in the outer circumferenceportion of the timing plate disk. As further shown in FIG. 7 and FIG. 8,the timing apertures 610 can allow light to pass between a light source660, such as an LED positioned above the timing plate, to a lightdetector 670, such as a photo resistor, positioned directly below theplate. In use, as the rotary display is rotated, a timing aperture canpass in alignment with a light detection assembly 650, comprising thelight source and light sensor. In one aspect, there can be at least onelight detection assembly, comprising a light source and a lightdetector, configured to selectively trigger the actuation or positioningof the bearings. Alternatively, as exemplified herein, there can be aplurality of light detection assemblies comprising a light source andlight sensor, whereby a single light detection assembly is dedicated toeach electromagnetic actuator and thus one for each row of dots in theBraille character cell.

Any light source and light sensor can be used however in the exemplifiedaspect, 3 light detectors and relays were bought as a kit from MPJA(Marlin P. Jones & Assoc., Inc., P.O. Box 530400, Lake Park, Fla.33403). To that end, exemplary light sensors that are suitable for useinclude those that are included in relay kit Stock No. 7863-KTcommercially available from MPJA. The light detectors can be mountedflush to the surface upon which the timing plate rotates into thesemounting apertures with, for example, a conventional epoxy resinadhesive. Likewise, three green LEDs (Cat. No. 276-1622, fromRadioShack, Fort Worth, Tex., USA) can for example be used to sensitizethe light detectors. The three relay kits can be connected to a powersupply with a breadboard from RadioShack (Experimentor 350 Cat. No.276-175). In the exemplified aspect, three power supplies can be used tomake the unit functional. One can be used for the relay/light detectorkits, one can be used to provide power to the electromagnets, and onecan be used to power the light source. Accordingly, FIG. 9 illustratesan exemplary schematic wiring diagram for the three power supplies. Asshown, the electromagnets can for example receive 5 volts atapproximately 2 amps each, and the light source can be connected inparallel to two 1.5 volt AA batteries connected in series to provide 3volts. Although the exemplified RBD utilizes three separate powersupplies, an alternative aspect can comprise a single power supply topower all three electrical subsystems of the display. In one aspect,this power supply/supplies can be integrated into the RBD itself or beconnected to the RBD through a power cord with an integrated powersupply/supplies.

As light from the LED passes through the aligned timing aperture definedby the timing disk, the light detector, such as a photo resistor, candetect and send a signal to a corresponding relay circuit which switchesthe connection in the relay and allows electric current to flow to anelectromagnetic actuator. This in turn enables the electromagnet togenerate a magnetic field which attracts a metallic ball bearing(s) andcauses the ball bearing to be lifted up through the divider plateaperture towards the top of the display assembly. When the selected ballbearing to be actuated is positioned in alignment with the pass-throughaperture in the stationary divider plate, the ball bearing will movefrom the lower chamber to the upper rotary chamber (or if the ballbearing is already in the upper rotary chamber, it will simply remainthere when the electromagnet is turned on). As the display continues torotate, the ball bearing will move past the pass-through hole in thedivider plate and come to rest on top of the middle stationary plate,resulting in a raised character dot comparable in size to regular JumboBraille.

In one aspect, the timing apertures can be aligned approximately 5°before the corresponding column of ball bearings, stop in between thetwo columns of ball bearings in a Braille character cell, and can beginagain and extend, for example, to a position that is approximately 5°beyond the second column of ball bearings. As one of skill in the artwill appreciate, this arrangement can ensure that the ball bearingreceives the correct actuation signal and has adequate exposure to thepass-through apertures in the stationary divider plate to be correctlyactuated per the actuation signal. The timing apertures can also beconfigured as slots approximately 1/16″ in width so that it allowsenough light to actuate one specific sensor. In still another aspect,and as exemplified in FIG. 6 b, the timing apertures can also beconfigured as slots that are tapered in a circumferential direction. Thecircumferential tapering can provide a diminishing or increasing levelof light passing through the aperture as the plate is rotated in eithera clockwise or counterclockwise direction. The increased or decreasedlevel of light passing through the timing aperture can be used todetermine which direction the Braille display is being rotated, therebyallowing a user to read forward or backward in the text being read onthe computer.

In an exemplary aspect, the timing plate can be connected to the bottomsurface of the lower rotary plate. In addition, the timing disk canfurther define a center mounting aperture through which a fixed supportpillar for connecting the stationary divider plate and stationarydivider plate mounts to the display base can be positioned.

In an alternative aspect, the timing apertures can be formed by anappropriately sized and shaped lower rotary plate, eliminating the needfor a separate timing disk. Still further, the timing disk can inanother aspect be primed and/or painted a dark color, such as forexample black. This can ensure that the light detectors will functionproperly and will not be confused by rouge light taking advantage of thetransparency of the timing disk material.

It is further contemplated in an alternative aspect that the timingplate can comprise any conventional mechanical mechanism capable oftriggering the selective actuation or positioning of a ball bearing. Forexample, a timing plate can be formed having a plurality of raisedpimples positioned in the outer circumference portion of the timingplate disk. In use, as the rotary display is rotated, a timing pimplecan pass in alignment with a trigger switch, thus resulting in selectiveactuation.

An optional bearing system can also be integrated in to the exemplifieddisplay device. A bearing system may be desired in some capacity toensure that the rotating motion of the display would always be as smoothand continuous as possible. An exemplary bearing system can be placedbetween the rotating disks and the axis about which they rotate. Tominimize any increase in the overall size of the display, the bearingsystem could, for example, comprise a relatively flat thrust needlebearing mounted between the display base and the timing disk to helpminimize friction as the rotary disk is turned by the user.

The display device can further comprise a base assembly constructed andarranged to support one or more components of the display device. Asshown in the exploded view of FIG. 10, the components of the rotarydisplay assembly can be mounted to a display base assembly 700. Inparticular, the rotary display assembly can be mounted to the baseassembly by a support pillar 750. In one aspect, the support pillar canbe a stationary pillar to which the stationary divider plate 260 can beconnect. Further, the mounted stationary divider plate can, in thisaspect, provide an axis of rotation about which the movable componentsof the rotary display assembly portion of the display can rotate, suchas for example, the upper and lower rotary plates and the timing plate.

In one exemplary aspect, three electromagnets 500 (and the threecorresponding LED-light sensor pairs) can be positioned directly abovethe top surface of the display along the back portion of the rotatingdisk. In particular, electromagnet mounting brackets 550 can be used tosuspend the electromagnets in overlying registration with theircorresponding row of Braille dots. In the exemplified aspect, the threeelectromagnets and LED-light sensor assemblies are further spacedapproximately 60° apart from each other, in order to prevent anyinterference from the adjacent electromagnets, and to allow forseparate, controlled actuation of each row of Braille dots.

A refreshable Braille display device of the present invention canfurther comprise a signal controller that interfaces between thecomputer text input and the RBD itself to send the correct signals atthe correct time to actuate the individual Braille dots in order to makethe Braille characters corresponding to the text on the computer. Thiscontroller can be a software package that would translate the writtenelectronic text from Word documents, Excel spreadsheets, web pages, etc.into binary inputs that are sent to a control circuit (one for eachelectromagnet) that either supplies electricity to the electromagnet(through the separate relay circuit) or doesn't, depending on whetherthe signal is a binary 1 (on) or 0 (off), corresponding to a signal fora single Braille dot actuation and non-actuation, respectively, or viceversa. Additionally, because the three electromagnetic actuators arespaced 60° apart along the back portion of the display, the binaryinputs to the control circuits for the electromagnets could be staggeredand the separate actuation of each row of the cell timed such that asthe user continuously rotates the display, each individual Braille cellis actuated in three separate sections of the display (by the threeseparate electromagnets, which are timed and activated by the threeLED-light sensor pairs) and then displayed as a complete Braille cell asthe user continues to rotate the cell around to the front of thedisplay.

Furthermore, this controller could also monitor the time elapsed sincethe last signal was received from the LED-light sensor combination.After a specific amount of time elapses without another signal beingreceived from the LED-light sensor combination (hence, the user is nolonger rotating the display), the controller would automatically shutoff any power to the electromagnets to avoid overheating or any otherpotentially hazardous situation. The power would then be restored to theelectromagnets when a signal was again received by the controller fromthe LED-light sensor combinations, indicating that the user is againrotating the display.

According to this aspect, it would be the responsibility of the controlsystem to produce the appropriate Braille text and to respond to userinput. The commands the user may wish to send to the reader can includethose which are typical of an electronic book reader (move forward, moveback, bookmark, dictionary and the like), and commands which arespecific to the motion-based Braille reader of this invention. Thelatter class of commands may include start/stop, speed adjustment andrepeat (play back of the last few words to clarify an uncertainty). Adisplay protocol may be implemented to aid identification of changes incontext, as when the user jumps to a different location in text or looksup a reference. One example of such a protocol includes a separator (abrief interval of blank Braille characters, for example) whereby theuser could be informed that the Braille characters following the blankinterval are from a new portion of the text being read.

It is contemplated that all of the electronic components in the displaydevice can be integrated into a display housing such that the RBD wouldbe one fully-contained unit. The electronic controller that supplies thenecessary input signal from the computer to the electromagnets couldalso be integrated into the RBD display housing. Thus, in one aspect,the display device can contain all of the subcomponents of theexemplified RBD, and would only require an interface to the computer itis being used with, such as a USB cable.

In use, the rotary display assembly consisting of the protective latexreading surface, ball bearings, upper rotary plate, lower rotary plate,and timing disk, can be rotated either manually or mechanically, i.e.,by a motor. As the display rotates, the user can read the Braille textthat is generated in each of the Braille character cells. While theformed characters are being read, character cells that have been readare continuously being refreshed and new characters are being created180° from the reading surface of the rotary display assembly.

Accordingly, in another aspect, the present invention provides a methodfor displaying a refreshable Braille character. The method generallycomprises providing a substantially planar Braille character displayassembly of the present invention having a plurality of bearing chambershave a bearing disposed therein to form plurality of Braille charactercell arrays configured to rotate about, and in a plane substantiallyperpendicular to, a rotary axis. As exemplified herein, at leas one ofthe plurality of bearing chambers of the Braille character cell arraycan be positioned in registration with a means for selectivelypositioning a bearing contained within the chamber. Once positioned, thebearing in the chamber can be selectively positioning in the upperportion of the bearing chamber to display a raised Braille characterdot. The raised Braille dot, or the raised bearing, can then bemaintained in the selectively raised position while the substantiallyplanar Braille character display assembly is rotated at least onerevolution about the rotary axis. These steps can be repeated until adesired number and pattern of bearings have been selectively positionedto display a desired Braille character cell.

For example, an exemplary sequence of the activation of all six Brailledots in a single Braille cell according to the present invention isillustrated schematically in FIGS. 11 a-11 g. Based on the geometry ofthe design, all six dots of a character are not actuated simultaneouslybut rather individually. Initially, the outermost dots are to beactuated, starting with the left-most one. Next, with these dotsactuated, the middle row of dots is to be actuated, again starting withthe left-most one. The innermost dots are actuated in a similar fashion.Therefore, after the character cell passes underneath the thirdelectromagnet, all six dots will have been actuated (or not actuated,depending on the character being created) and the Braille character iscomplete. The refreshing of the character begins when the characterfirst traverses the first electromagnet after passing by the user.

As shown in FIG. 11 a, a user initially rotates the refreshable Brailledisplay device reading surface as he/she reads the Braille text. Withreference to FIG. 11 b, as the timing aperture for bearing #1 (B1)reaches the light sensor, light passes through the timing aperture and asignal is sent from the light sensor to the signal controller. If thesignal controller has received a signal to actuate this particularBraille dot, this turns on the electromagnet above B1, and causes the B1ball bearing to be lifted up into the top position. In FIG. 11 c, as theuser continues to rotate the display, B1 will remain in the topposition. Just as in FIG. 11 b, as the timing aperture for bearing B2reaches the light sensor, a signal is sent from the light sensor to thesignal controller. If the signal controller has received a signal toactuate this particular Braille dot, this turns on the electromagnetabove bearing B2. Just as before, this causes bearing B2 to be lifted upinto the raised position. As the user continues to rotate the display,bearing B2 will also remain in the raised position. As the usercontinues to read and rotate the display, the Braille cell containingbearing B1 and B2 reaches the next light sensor-electromagnet actuatorcombination. In FIG. 11 d, as light passes through the timing aperturefor bearing B3, B3 is actuated or positioned into the raised positionjust as B1 and B2 were, and will remain in the top position as the usercontinues to rotate the display. As the user continues to rotate thedisplay, B4 will be the next bearing actuated in the same manner asbearing B1, B2, and B3, and will remain in the raised position as theuser continues to rotate the display. As the user further continues toread and rotate the display, the Braille cell containing bearings B1,B2, B3, and B4 reaches the next light sensor-electromagnet actuatorcombination. As light passes through the timing aperture for bearing B5,bearing B5 is actuated into the raised position just as bearings B1, B2,B3, and B4 were and will remain in the upper raised position as the usercontinues to rotate the display. Still further, as the user continues torotate the display, bearing B6 will be actuated in the same manner asB1, B2, B3, B4, and B5, and will remain in the top position as the usercontinues to rotate the display. Now all of the six dots in thisparticular Braille cell are actuated, and as the user continues torotate the display around, the newly actuated cell will reach thereading position, as depicted above. In the exemplified aspect, it iscontemplated that there are 30 Braille cells positioned around thecircumference of the display. Thus, as the user continues to read theBraille characters, he/she will rotate the display to bring the nextBraille character into the reading position. This rotation is whatcauses the actuation that has just been described.

Lastly, it should be understood that while the present invention hasbeen described in detail with respect to certain illustrative andspecific aspects thereof, it should not be considered limited to such,as numerous modifications are possible without departing from the broadspirit and scope of the present invention as defined in the appendedclaims.

1. A refreshable Braille display device comprising, a Braille characterdisplay assembly comprising: a lower rotary plate defining a pluralityof lower bearing wells, each lower bearing well configured to house abearing; an upper rotary plate having a substantially planar readingsurface and defining a plurality of upper bearing wells configured toreceive a bearing, the upper rotary plate being positioned in overlyingregistration with and connected to the lower rotary plate such that eachupper bearing well is in overlying registration with one of theplurality of lower bearing wells to provide a plurality of bearingchambers, wherein the plurality of bearing chambers each have a bearingdisposed therein and form at least one Braille character cell arrayconfigured to rotate about, and in a plane substantially perpendicularto, a rotary axis; and a stationary plate disposed between the lower andupper rotary plates and defining a plurality of apertures configured toselectively allow communication between the respective bearing wellswhen a lower bearing well and an upper bearing well are each positionedin registration with one of the plurality of apertures; and a means forselectively positioning the bearing in at least one bearing chamber inthe respective upper or lower bearing wells of the character cell arraywhen communication between the respective bearing wells is selectivelyallowed.
 2. The refreshable Braille display device of claim 1, whereinthe at least one Braille character cell array is comprised of an arrayof at least six bearing chambers.
 3. The refreshable Braille displaydevice of claim 2, wherein the character display assembly comprises atleast two Braille character cells arranged radially about, and in aplane substantially perpendicular to, the rotary axis.
 4. Therefreshable Braille display device of claim 1, wherein the upper rotaryplate has a thickness less than the diameter of the bearing housedwithin the bearing chambers.
 5. The refreshable Braille display deviceof claim 1, wherein the lower rotary plate has a thickness equal to orgreater than the diameter of the bearing housed within the bearingchambers.
 6. The refreshable Braille display device of claim 1, whereinat least three pass through apertures are formed by the stationarydivider plate.
 7. The refreshable Braille display device of claim 1,wherein the bearings are comprised of a magnetic metal.
 8. Therefreshable Braille display device of claim 1, wherein the means forselectively positioning the bearing in at least one bearing chamber inthe respective upper or lower bearing wells comprises an electromagnetregistered with at least one of the plurality of pass through aperturesof the stationary divider plate.
 9. The refreshable Braille displaydevice of claim 6, wherein the means for selectively positioning thebearing in at least one bearing chamber in the respective upper or lowerbearing wells comprises at least three electromagnets and wherein eachof the at least three electromagnets is registered with one of the atleast three pass through apertures of the stationary divider plate. 10.The refreshable Braille display device of claim 1, further comprising ameans for regulating the selective positioning of the bearings withinthe bearing chambers.
 11. The refreshable Braille display device ofclaim 2, wherein the means for regulating comprises a light source, alight detector, and timing plate configured to selectively allow lightto communicate from the light source to the light detector.
 12. Therefreshable Braille display device of claim 11, wherein the means forregulating comprises at least three light sources and at least threelight detectors, and wherein each light detector is configured toselectively detect light from one of the at least three light sources.13. The refreshable Braille display device of claim 1, furthercomprising a flexible bearing retention layer disposed on the planarreading surface of the upper rotary plate.
 14. The refreshable Brailledisplay device of claim 13, wherein the flexible bearing retention layeris comprised of latex.
 15. The refreshable Braille display device ofclaim 1, further comprising a means for mechanically rotating thedisplay assembly about the rotary axis at a predetermined rate ofrotation.
 16. A method for displaying a refreshable Braille character,comprising: a) providing a substantially planar Braille characterdisplay assembly comprising a plurality of bearing chambers, wherein theplurality of bearing chambers each have a bearing disposed therein andform a plurality of Braille character cell arrays configured to rotateabout, and in a plane substantially perpendicular to, a rotary axis; b)positioning at least one of the plurality of bearing chambers of theBraille character cell array in registration with a means forselectively positioning a bearing; c) selectively positioning thebearing in the bearing chamber of step b) in an upper portion of thebearing chamber to display a raised Braille character dot; and d)maintaining the selectively positioned bearing of step c) in the upperportion of the bearing chamber while the substantially planar Braillecharacter display assembly is rotated at least one revolution about therotary axis.
 17. The method of claim 16, wherein the at least onebearing chamber of step b) is selectively positioned in registrationwith the selective positioning means by rotating the substantiallyplanar Braille character display assembly about the rotary axis.
 18. Themethod of claim 16, wherein the bearing of step c) is selectivelypositioned in the respective upper bearing well by applying anelectromagnetic force to the bearing.
 19. The method of claim 16,further comprising repeating steps b), c), and d) until a plurality ofbearings are selectively positioned in the respective upper portions ofthe respective bearing chambers to display a desired Braille character.20. The method of claim 16, further comprising refreshing theselectively positioned bearing of step c) by selectively positioning thebearing in a lower portion of the bearing chamber after the bearingchamber has made at least one complete revolution about the rotary axis.